1. Field of the Invention
A brake pad apparatus. More particularly, a brake pad apparatus including at least one projection extending past an insulating layer of the brake pad apparatus for being engaged by a pressing member of a brake assembly.
2. Description of the Prior Art
Conventional disc brake assemblies for vehicles generally include a pair of brake pads which are disposed on opposing sides of a brake rotor and are drawn against the rotor to create a frictional clamp force, which in turn slows the vehicle. The frictional clamp force is typically generated by way of at least one hydraulic pressure-actuated pressing member, such as a piston, which is contained in a brake caliper that pushes against one of the pads. On typical fixed-caliper type brake assemblies, the pressing member is a piston which is drawn against both the inboard and outboard pads, whereas on floating-caliper type brake assemblies, a piston-style pressing member is drawn against the inboard pad and a pair of caliper finger-style pressing members are drawn against the outboard pad.
Brake pads typically include a planar backing plate that has an inside surface and an outside surface. A liner, i.e., friction material, is connected to the inside surface of the backing plate for contacting the rotor to create the frictional clamping force against the rotor. It is further known in the art to attach an insulating layer, i.e., a shim, to the outside surface of the backing plate to provide noise and heat insulation during contact of the liner against the rotor. The insulating layer usually covers a large portion of the backing plate area, including the area that is directly aligned with the contact face of the piston(s), and in the case of floating calipers, under the caliper fingers on the outboard side. Therefore, the insulating layer is engaged by the piston(s)/caliper fingers during compression of the brake pad.
Along with the positive insulative characteristics that are provided by the insulating layer, it has also been recognized that as a result of the pressing member directly engaging the insulating layer, the brake assembly may be subjected to higher drag torque and larger amounts of brake fluid consumption (displacement). An important metric to caliper performance is minimizing drag torque and fluid consumption of which total compliance of the caliper housing and brake pad assemblies is a major contributor. Accordingly, there remains a need for improvements to such brake pad apparatuses to provide better performance characteristics during operation of the brake assembly.